Surveying the Environmental Footprint of Urban Food Consumption

Assessments of urban metabolism (UM) are well situated to identify the scale, components, and direction of urban and energy flows in cities and have been instrumental in benchmarking and monitoring the key levers of urban environmental pressure, such as transport, space conditioning, and electricity. Hitherto, urban food consumption has garnered scant attention both in UM accounting (typically lumped with “biomass”) and on the urban policy agenda, despite its relevance to local and global environmental pressures. With future growth expected in urban population and wealth, an accounting of the environmental footprint from urban food demand (“foodprint”) is necessary. This article reviews 43 UM assessments including 100 cities, and a total of 132 foodprints in terms of mass, carbon footprint, and ecological footprint and situates it relative to other significant environmental drivers (transport, energy, and so on) The foodprint was typically the third largest source of mass flows (average is 0.8 tonnes per capita per annum) and carbon footprint (average is 2.1 tonnes carbon dioxide equivalents per capita per annum) in the reviewed cities, whereas it was generally the largest driver of urban ecological footprints (average is 1.2 global hectares per capita per annum), with large deviations based on wealth, culture, and urban form. Meat and dairy are the primary drivers of both global warming and ecological footprint impacts, with little relationship between their consumption and city wealth. The foodprint is primarily linear in form, producing significant organic exhaust from the urban system that has a strong, positive correlation to wealth. Though much of the foodprint is embodied within imported foodstuffs, cities can still implement design and policy interventions, such as improved nutrient recycling and food waste avoidance, to redress the foodprint.     

Ranking of invasive spread through urban green areas in the world’s 100 most populous cities

Urban landscapes are highly fragmented (leading to the extinction of native species) as well as transformed and disturbed (creating novel environments). Such conditions provide non-native species with opportunities to establish and spread through “urban green areas” (UGAs). UGAs can serve as stepping stones for many alien species to recruit and may become sources of propagules to launch invasions in adjoining natural ecosystems. There is great diversity in the spatial structures of UGAs worldwide; these are determined by the city’s level of development, human density, urban planning policy, and history. We explore the invasion risks of, and the potential of invasive spread in, UGAs in the world’s 100 most populous cities (in 40 countries). Based on maps of enhanced vegetation index at 250 m resolution over the extent of 25 by 25 km for each city centre, we simulate the invasion and spread of a reference species (a virtual ruderal invasive species) from the city centre into surrounding urban or rural areas. Doing so allowed us to provide an objective baseline for comparing urban susceptibility to such invasions across diverse cultures, histories and societies. We derive the global ranking of invasive spread potential for each city based on the rate of spread of the reference species, and the ranking of 40 countries, based on the average rate of spread in their cities. We explore correlates of spread rates after 100 time steps (years) by examining the roles of climate (mean annual temperature and rainfall), human demography (city population size and growth rate), and socio-economic indicators [human footprint, human development index and gross domestic product (GDP) per capita]. Small city population size and high GDP per capita are the only significant predictors of high potential for invasive spread. Among the G20 countries, Canada, South Korea, South Africa, France, USA and Brazil all feature in the top-10 countries, and Atlanta, Washington, D.C. and Dallas in the USA, Chittagong in Bangladesh, Toronto in Canada and Brasilia in Brazil are listed among the top 10 cities overall. Our results can serve as a global baseline assessment of invasive spread risks through UGAs, and call for improved protocols for monitoring, planning and management of UGAs.     

Urban Scaling of Cities in the Netherlands

We investigated the socioeconomic scaling behavior of all cities with more than 50,000 inhabitants in the Netherlands and found significant superlinear scaling of the gross urban product with population size. Of these cities, 22 major cities have urban agglomerations and urban areas defined by the Netherlands Central Bureau of Statistics. For these major cities we investigated the superlinear scaling for three separate modalities: the cities defined as municipalities, their urban agglomerations and their urban areas. We find superlinearity with power-law exponents of around 1.15. But remarkably, both types of agglomerations underperform if we compare for the same size of population an agglomeration with a city as a municipality. In other words, an urban system as one formal municipality performs better as compared to an urban agglomeration with the same population size. This effect is larger for the second type of agglomerations, the urban areas. We think this finding has important implications for urban policy, in particular municipal reorganizations. A residual analysis suggests that cities with a municipal reorganization recently and in the past decades have a higher probability to perform better than cities without municipal restructuring.     

Variations in air quality during rapid urbanization in Shanghai,China

Shanghai is the largest commercial and industrial city of China, but air quality issues have hindered its development in becoming a “global city.” This study used monitoring data on SO₂, NO _x , acid rain pH, dustfall, and total suspended particles (TSP) from the Shanghai Environmental Monitoring Center to evaluate and analyze the air quality in urban, suburban, and rural areas during the period 1983–2005. The results showed that the spatial pattern of air parameters was determined by the level of urbanization; thus, the higher the level of urbanization, the worse the air quality. On the whole, the atmospheric environment of the three spatial regions improved gradually because of economical growth and environmental protection since the 1990s. For the entire region of Shanghai, the relationship between the integrated air quality index and gross domestic product (GDP) per capita was an N-shaped environmental Kuznets curve (EKC) due to decreasing air quality in suburban and rural areas this century. Thus, environmental controls should be increased in Shanghai, especially in developing suburban and rural areas during rapid urbanization.     

Urban scaling and its deviations: revealing the structure of wealth, innovation and crime across cities

With urban population increasing dramatically worldwide, cities are playing an increasingly critical role in human societies and the sustainability of the planet. An obstacle to effective policy is the lack of meaningful urban metrics based on a quantitative understanding of cities. Typically, linear per capita indicators are used to characterize and rank cities. However, these implicitly ignore the fundamental role of nonlinear agglomeration integral to the life history of cities. As such, per capita indicators conflate general nonlinear effects, common to all cities, with local dynamics, specific to each city, failing to provide direct measures of the impact of local events and policy. Agglomeration nonlinearities are explicitly manifested by the superlinear power law scaling of most urban socioeconomic indicators with population size, all with similar exponents (1.15). As a result larger cities are disproportionally the centers of innovation, wealth and crime, all to approximately the same degree. We use these general urban laws to develop new urban metrics that disentangle dynamics at different scales and provide true measures of local urban performance. New rankings of cities and a novel and simpler perspective on urban systems emerge. We find that local urban dynamics display long-term memory, so cities under or outperforming their size expectation maintain such (dis)advantage for decades. Spatiotemporal correlation analyses reveal a novel functional taxonomy of U.S. metropolitan areas that is generally not organized geographically but based instead on common local economic models, innovation strategies and patterns of crime.     

中国城市生态与经济社会协同性评估

为认识城市经济社会和生态的协同特征,本研究基于城市人均绿地面积、人均GDP和人均期望寿命等构建城市生态与经济社会功能协同性指标评价体系,建立城市生态与经济社会协同性指数评价方法。通过比较中国35个典型城市的协同性指数与功能综合得分,分析了中国城市协同性特征,并按照城市规模、行政区类型分析城市协同性差异和城市功能综合得分差异,对协同水平进行分类。结果表明: 2016年,中国35个城市生态与经济社会平均协同性指数为28.79,协同性最强城市的协同性指数为3.83,最弱的城市为63.04,表明中国城市协同性不高且城市间差异较大。协同性指数、城市经济功能、社会功能与城市人口规模、经济规模呈显著正相关。不同人口规模、经济规模、不同行政职能城市之间协同性指数差异具有显著性。中国城市化总体仍处于功能失衡的发展阶段,城市发展有利于各城市功能性提高但并未有效提升协同性,生态功能的高低显著影响城市协同性,城市生态功能不高是当前中国城市协同性高低的主要制约因素。     

浙江三大城市群绿色发展效率时空分异及影响机理

提升浙江三大城市群绿色发展效率是浙江加快建成美丽中国先行示范区的重要途径之一.以三大城市群包含的41个县(市)为依托,以2000-2019年县域面板数据为样本,将超效率SBM模型与窗口分析及测度效率相结合,运用空间计量分析方法研究效率的空间分布及区域差异,并借助面板固定效应模型探索效率的差异化影响机理.结果 表明:研究...     

“双碳”目标下闽三角碳排放脱钩状态及驱动机制分析

快速城市化背景下，建设低碳城市群是实现"双碳"目标的最佳方式。在碳排放核算的基础上，使用Tapio脱钩模型和LMDI方法对闽三角以及厦门、漳州和泉州的脱钩状态和碳排放的驱动机制进行了研究。主要结论如下：（1）2005-2017年闽三角碳排放和人均碳排放均持续增加，二者有相同的变化趋势。闽三角的工业中心泉州有最高的碳排放和人均碳排放。发展型城市漳州碳排放最低，但碳排放和人均碳排放增长率均最高。服务型城市厦门碳排放增长率最低。（2）闽三角的脱钩状态逐渐改善，平均脱钩系数为1.03，脱钩状态为扩张性连接。厦门、漳州和泉州的平均脱钩系数分别为0.45、2.70和1.10，3个城市分别以弱脱钩、扩张负脱钩和扩张性连接状态为主。（3）人均GDP和人口规模是闽三角碳排放的正向因素，能源结构和能源强度是负向因素。正向因素的贡献在下降，负向因素的贡献在升高。人均GDP和能源结构分别对漳州和厦门碳排放有最强的促进和抑制效应。能源强度对3个城市碳排放变化的效应不同。（4）人口扩张促进碳排放增加，使碳排放与经济发展无法脱钩。人口规模对闽三角碳减排无脱钩努力。能源结构优化和能源强度下降有助于碳排放与经济发展脱钩，是闽三角碳减排的强脱钩努力和弱脱钩努力。能源强度对泉州碳减排无脱钩努力。优化能源结构是闽三角实现碳减排和"双碳"目标的关键。已经脱钩的厦门宜尽早制定碳达峰行动计划，引领闽三角的碳达峰行动。漳州可通过升级产业结构实现减排。泉州必须提升能源效率才能降低碳排放。     

中国城市低碳发展水平评估方法研究

城市低碳发展水平评估对推动城市可持续发展,提高城市应对气候变化能力具有重要意义。基于低碳城市理念和内涵,构建了由6类(碳排放、经济发展、社会进步、交通、人居环境和自然环境)、13个具体指标组成的城市低碳发展评价指标体系及综合评价指数,并结合中国35个城市2010—2015年社会经济发展数据,对参评城市的低碳发展水平及趋势进行评价与分析。结果表明:多数参评城市的低碳发展水平呈现上升的趋势,其中,城市低碳发展水平最高和最低城市名单无明显变化,且深圳市在2010年和2015年均为低碳发展水平最高的城市。与2010年相比,杭州市、银川市、郑州市、石家庄市和昆明市的城市低碳发展指数相对持平,而成都市、长沙市、合肥市和大连市有所下降。城市低碳发展水平较低可能是由于城市碳排放、经济、社会、交通、人居环境和自然环境等方面之间协调发展程度不够造成的。最后,对如何提高我国城市低碳发展水平给出了对策和建议。     

A Burning Issue: Rethinking the Transition from Hunter‐Gatherer to Industrial Sociometabolic Regimes

Hunter‐gatherers are commonly seen as having a fundamentally different sociometabolic regime from agrarian and industrial societies because they are thought to directly appropriate the products of natural ecosystems without modifying those systems in order to enhance their productivity. However, ethnographic and archeological evidence reveals that many hunter‐gatherers extensively employed fire to manage their ecosystems so as to increase production of desirable wild resources, thus engaging in “colonization of nature” that is not qualitatively different from that practiced by other types of society. They systematically burned wild vegetation in order to increase populations of edible wild plants consumed by humans and promote growth of forage for game animals. Deliberate ecosystem burning by Australian Aborigines represented an energy expenditure of 1,512 gigajoules per capita per year (GJ/capita/yr), a level of energy use that is more than three times higher than the United States (445 GJ/capita/yr). It is their profligate consumption of biomass energy that explains why the quality of life of many hunter‐gatherers was often better than that of traditional settled peasant farmers. Hence, the extent to which hunter‐gatherers have a distinct type of sociometabiolic regime is called into question. It can be argued that in the course of social evolution, there have been only two sociometabolic regimes. In one type, which includes hunter‐gatherers, swidden agriculturalists, and industrial societies, extrasomatic energy does most of the productive work, whereas in the other type, that of premodern settled agriculturalists, production is largely dependent on human muscle power.     

Wealth as a source of density dependence in human population growth

In modern industrialized countries, human birth rates have been declining persistently for decades. In many cases they have now fallen below the replacement threshold. However, unlike in natural populations where population growth is constrained by limited resources, birth rates in modern industrialized countries are negatively correlated with resource availability. Here, declining birth rates in human populations are shown to be a manifestation of density‐dependent population growth brought on by socioeconomic development. This is demonstrated by combining empirical power law relations between population size, gross domestic product (GDP) per capita, and fertility in a simple theoretical model describing population dynamics in developed countries. For a closed population, the model exhibits growth to a globally stable equilibrium population size, for both national and city populations. A version of the model that is open with respect to immigration and the influence of foreign technology and capital exhibits a good fit to long‐term time series data on population size, GDP per capita, and birth rates for the United States, France and Japan.     

Economic status and temperature-related mortality in Asia

In developed countries, low latitude and high temperature are positively associated with the population’s ability to adapt to heat. However, few studies have examined the effect of economic status on the relationship between long-term exposure to high temperature and health. We compared heterogeneous temperature-related mortality effects relative to the average summer temperature in high-socioeconomic-status (SES) cities to temperature-related effects in low-SES cities. In the first stage of the research, we conducted a linear regression analysis to quantify the mortality effects of high temperature (at or above the 95th percentile) in 32 cities in Taiwan, China, Japan, and Korea. In the second stage, we used a meta-regression to examine the association between mortality risk with average summer temperature and gross domestic product (GDP) per capita. In cities with a low GDP per capita (less than 20,000 USD), the effects of temperature were detrimental to the population if the long-term average summer temperature was high. In contrast, in cities with a high GDP per capita, temperature-related mortality risk was not significantly related to average summer temperature. The relationship between long-term average summer temperature and the short-term effects of high temperatures differed based on the city-level economic status.     

生态压力视角下福建省区域经济协调发展研究

基于生态压力人口模型, 采用标准差椭圆分析、基尼系数法和基于最大值灰色关联聚类等方法, 分析了福建省域生态压力的时空分布特征, 揭示了生态压力的极化状况, 划分了不同生态压力水平的经济区, 提出了省域经济协调发展调控策略。结果表明: (1)福建省域生态压力的空间格局呈显著的“山海分异”特征, 即生态压力的分布范围主要集中于东南沿海一线, 而西北部山区所受压力较小, 且随着沿海次中心城市在研究期内不断发展,“山海分异”的格局被进一步强化。(2)省域生态压力人口分布体现了高度极化特征, 从最高级城市到最低级城市生态压力人口呈指数型递减。省域经济发展仍处于持续高度不平衡阶段, 省域经济协调发展的基本面总体向好, 但不够稳定。(3)9大设区市按生态压力水平可划分为3类, 分别为高压经济区(福州、厦门、泉州)、中压经济区(漳州、莆田、宁德)和低压经济区(三明、南平、龙岩)。综合上述结果本研究认为亟需构建以优化增长极、强化增长点、显化增长轴、内化承接带、外化活力港、深化辐射网为内容的区域经济协调发展“6化”调控框架。     

泛长三角地区碳生态效率的空间格局及影响因素

碳生态效率反映碳排放产出的经济社会价值高低,是衡量可持续发展水平的重要指标。以泛长三角各市为对象,以揭示碳排放的经济社会效益为目标,构建经济产出效率和人口承载效率评估指标,研究碳生态效率的空间格局和影响因素。结果表明：经济产出效率和人口承载效率呈现不同的变化趋势和空间格局,2000-2014年,经济产出效率增长97%,人口承载效率下降68%,前者空间集聚度高于后者;核心区及部分沿江城市的经济产出效率较高、增长较快,人口承载效率较低、下降较慢,碳生态效率高于其他城市;经济产出和人口承载效率的影响因素类似、作用强度和方向不同,前者主要受产业结构促进,后者的影响因素包括但不限于产业结构,但产业结构优化抑制了人口承载效率提升。研究认为,经济和社会视角的碳生态效率变化趋势及影响因素作用方向存在差异,为通过政策调控实现经济和社会效益同步提升增加了难度,在推动经济增长的同时,进一步加快人口集聚、优化产业结构和能源结构、提高能源利用效率等是政策制定的优选方向。     

Endless Urban Growth? On the Mismatch of Population,Household and Urban Land Area Growth and Its Effects on the Urban Debate

In European cities, the rate of population growth has declined significantly, while the number of households has increased. This increase in the number of households is associated with an increase in space for housing. To date, the effects of both a declining population and decreasing household numbers remain unclear. In this paper, we analyse the relationship between population and household number development in 188 European cities from 1990–2000 and 2000–2006 to the growth of urban land area and per capita living space. Our results support a trend toward decreasing population with simultaneously increasing household number. However, we also found cites facing both a declining population and a decreasing household number. Nevertheless, the urban land area of these “double-declining” cities has continued to spread because the increasing per capita living space counteracts a reduction in land consumption. We conclude that neither a decline in population nor in household number “automatically” solve the global problem of land consumption.     

A life‐cycle assessment model for zero emission neighborhoods

Buildings represent a critical piece of a low‐carbon future, and their long lifetime necessitates urgent adoption of state‐of‐the‐art performance standards to avoid significant lock‐in risk regarding long‐lasting technology solution choices. Buildings, mobility, and energy systems are closely linked, and assessing their nexus by aiming for Zero Emission Neighborhoods (ZENs) provides a unique chance to contribute to climate change mitigation. We conducted a life‐cycle assessment of a Norwegian ZEN and designed four scenarios to test the influence of the house size, household size, and energy used and produced in the buildings as well as mobility patterns. We ran our scenarios with different levels of decarbonization of the electricity mix over a period of 60 years. Our results show the importance of the operational phases of both the buildings and mobility in the neighborhood's construction, and its decline over time induced by the decarbonization of the electricity mix. At the neighborhood end‐of‐life, embodied emissions then become responsible for the majority of the emissions when the electricity mix is decarbonized. The choice of functional unit is decisive, and we thus argue for the use of a primary functional unit “per neighborhood,” and a second “per person.” The use of a “per m²” functional unit is misleading as it does not give credits to the precautionary use of floor area. To best mitigate climate change, climate‐positive behaviors should be combined with energy efficiency standards that incorporate embodied energy, and absolute threshold should be combined with behavioral changes.     

Impact of Illness and Medical Expenditure on Household Consumptions: A Survey in Western China

Background

The main goal of this study is to examine the associations between illness conditions and out-of-pocket medical expenditure with other types of household consumptions. In November and December of 2011, a survey was conducted in three cities in western China, namely Lan Zhou, Gui Lin and Xi An, and their surrounding rural areas.

Results

Information on demographics, income and consumption was collected on 2,899 households. Data analysis suggested that the presence of household members with chronic diseases was not associated with characteristics of households or household heads. The presence of inpatient treatments was significantly associated with the age of household head (p-value 0.03). The level of per capita medical expense was significantly associated with household size, presence of members younger than 18, older than 65, basic health insurance coverage, per capita income, and household head occupation. Adjusting for confounding effects, the presence of chronic diseases was negatively associated with the amount of basic consumption (p-value 0.02) and the percentage of basic consumption (p-value 0.01), but positively associated with the percentage of insurance expense (p-value 0.02). Medical expenditure was positively associated with all other types of consumptions, including basic, education, saving and investment, entertainment, insurance, durable goods, and alcohol/tobacco. It was negatively associated with the percentage of basic consumption, saving and investment, and insurance.

Conclusions

Early studies conducted in other Asian countries and rural China found negative associations between illness conditions and medical expenditure with other types of consumptions. This study was conducted in three major cities and surrounding areas in western China, which had not been well investigated in published literature. The observed consumption patterns were different from those in early studies, and the negative associations were not observed. This study may complement the existing rural studies and provide useful information on western Chinese cities.     

Scaling in urban building energy use and its influencing factors

Several studies have reported scaling relationships for energy consumption with respect to city size and other indicators. However, such scaling relationships have rarely been reported at the suburban level. This study explored the scaling relationships between energy use (EU) and building size (gross floor area [GFA]) at the building level in 16 urban regions in the United States from 2011 to 2019. We found that the scaling exponents of most of the examined regions changed from either super-linear or sub-linear to linear (β = 1) over the years. The scaling exponents of some cities (e.g., New York City) fluctuated around 1. These scaling exponents are negatively correlated with regional climate. This study reports that the scaling relationships between energy consumption and GFA at the building level in heterogeneous cities are evolving toward linear scaling. This study also found that different building types and building energy structures significantly impact building energy consumption. Hotels in New York City had the highest scaling exponent (β = 1.02), and strong correlations were observed between the scaling exponents and the share of electricity in building EU. These insights reveal the common nature of the relationships between building EU and GFA and the intersections between scaling exponents and building attributes. Our study highlights the importance of energy efficiency management in hotels and electricity-dominated buildings.     

Estimation of Copper In‐use Stocks in Nanjing,China

Copper (Cu) is an essential but supply‐restricted resource in China. Characterization of in‐use stocks can provide useful instruction for the future recycling of copper. This article attempts to estimate copper in‐use stocks in a Chinese city. To this purpose, an extensive bottom‐up estimate of copper stocks in use in Nanjing in the year 2009 was conducted. The results are a total stock estimate of 295 gigagrams (Gg) of copper or 46.9 kilograms (kg) of copper per capita for 2009. Infrastructure, equipment, and buildings contain 42.0%, 26.1%, and 28.1% of the total stock, respectively, indicating that these three categories are principal potential reservoirs of a secondary copper resource. The copper in transportation amounts to only about 3.7% of the total amount. The per capita stock was compared with similar studies carried out in other regions of the world, and the results show that the Nanjing level is significantly lower than developed countries. On the whole, our results show that electric power transmission and distribution systems, buildings, household durables, and industrial equipment are the four largest potential reservoirs of copper scrap.     

Analysis of the impact of ancient city walls on urban landscape patterns by remote sensing

As the most important construction features of ancient Chinese cities, the city walls nowadays have lost their function of enemy defense and turned to affect the urban structure and development. To clarify the impact of ancient city walls on modern urban development, this work was conducted to measure the differences of landscape types and levels between the inner and outer walls of three typical ancient Chinese cities with the help of geoinformatics materials and landscape ecology indices. The results of this research proved that city walls have great impact on landscape pattern. Specifically, the aggregation, fragmentation, diversity and evenness of landscape were strongly affected by well-preserved ancient city walls. By sorting out and consulting historical documents and China's “City Walls Protection Regulations”, we also found that city walls help the old city to retain its original style and design characteristics. The findings of this quantitative-analysis-based historical study can provide a theoretical basis for the protection of historical heritage and landscape design.